1. Introduction
There were seven operating open pit copper–molybdenum (Cu–Mo) operations in
British Columbia (BC), Canada, in 2014. Figure 1 shows that these pits are scattered in
a 700 km long band along the centre of the province. All the mines exploit large porphyry
ore deposits with low Cu–Mo grades. These open pit mines range in age from
roughly 50 years for Highland Valley Copper (HVC) and Endako mines to just one
year of production for Mt. Milligan mine, which is a copper and gold mine. HVC’s
Valley pit is Canada’s largest and deepest open pit with depth of approximately 800 m.
Rock slope movements are monitored at these mines to help manage the stability of
the pit walls. Unanticipated pit wall failures can have serious consequences on the
safety and economics of an open pit operation. This was recently highlighted by the
large pit wall failure at the Bingham Canyon mine in Utah in April 2013 where significant
production and economic losses were caused by the failure [1].
Many new monitoring technologies have been developed over the operating lives of
the BC mines. While BC’s open pit Cu–Mo mines have often tested and evaluated
newer monitoring techniques, the mining industry has generally been slow to accept
and routinely use new technologies. The purpose of this paper is to summarise and discuss
current rock slope monitoring practices used by open pit Cu–Mo porphyry mines
in BC.